Biomedical device, method for manufacturing the same and use thereof

ABSTRACT

A three-dimensional biomedical device having an osteoinductive first area with a controlled porosity and a second area, which is produced by laser technology from a powder including one of ceramics, metals, metal alloys, bioactive glasses, lead zirconate titanate and biocompatible polymers, or mixtures thereof. The ratio of the porosities from the second area to the first area is equal or less than one, preferably from 0.001 to 0.9. A method for manufacturing the device for fitting in a bone defect, wherein a virtual object is designed with a computer-aid designed software, and the device is manufactured by laser technology including layering a powder onto a plate ( 7 ) so that a layer of a predetermined thickness is formed; the laser beam ( 8 ) selectively processes the powder to produce a processed layer, and, thus, layer after layer, the layers are joined together until the biomedical device is formed.

FIELD OF INVENTION

This invention relates to the field of the manufacture of implants formedical and/or orthopedic applications, such as for example prostheses,orthodontia, bone implants, preferably cranial implants. More precisely,the present invention relates to a method of manufacturing a biomedicaldevice from ceramic or metal powder, using a laser technology.

BACKGROUND OF THE INVENTION

The growing search for new materials for orthopedic or reconstructionsurgery, lead to the development, in the last two decades, of biomedicaldevices based on ceramics, such as hydroxyapatite and tricalciumphosphate. These ceramic materials were recognized as biocompatible andas having an osseoconductive behavior, and were thus used for the repairor replacement of bone defects.

Aiming a controlled porosity of these materials while keepingsatisfactory mechanical properties, remains the technical challenge ofthese biomaterials. Efforts in manufacturing porous ceramics withinterconnected pores have been made JP order to enhance tissue growth.It is known that a porous and interconnected structure allows new tissueto penetrate the substrate, and stimulates the growth of new bonetissue.

For example, WO2009/053835, as well as a number of the prior artdocuments in the field, reports a method to make biomedical devices withcontrolled porosity, involving the replication in ceramics of3D-substrates such as polymeric substrates, which are eliminated at theend of the process by sintering. This method has the disadvantage ofnecessitating several steps, first for the manufacture of the substrateand second for the elimination/release of the substrate. Furthermore,the release of the substrate is susceptible to result in crackingphenomena on the thin walls of the piece. To avoid these drawbacks,additives are used. Most of the time, these additives are notbiocompatible. Moreover, there is a remaining high risk that the step ofelimination of the substrate may cause a distortion in the work piecedue to variations of the dimensions during the warm-up. For thesereasons, elimination of the substrate may be a hazardous step that thepresent invention intends to avoid.

The present invention is thus advantageous, in that the process of theinvention involves direct laser treatment of the powder without use of asubstrate, which is time effective, avoids the risk of distortion of thework piece, and is free of additives. Consequently, the productresulting from the manufacturing process of the invention is also freeof additives.

Some prior art documents related to ceramic devices avoid the use ofpolymeric substrates and directly mix powders, such as for example, U.S.patent application 20070210493. This U.S. patent application reports themanufacture of porous ceramics based on slurry prepared from by mixingalumina particles, glass fit, silica particles, silica sol and water.This mixture is set in a plate, dried and sintered in order to obtain ahard and resistant ceramic. However, this method leads to a filter forfiltering fluid such as liquid and gas or the like, and is not adaptedfor a biomedical device.

Further prior art relates to methods of manufacturing three-dimensionalobjects by laser technology. U.S. Pat. No. 4,863,538 for example,reports how to make a three-dimensional objet from a powder of plastic,metal, polymer, ceramic powders, or composite materials. The reportedmethod is a layer-wise method: the powder is dispensed into a targetarea where the laser selectively sinters the powder to produce asintered layer; the layers are joined together until the completed partis formed.

Technical Issue

There is thus still a need for simple methods for manufacturingbiocompatible implants, avoiding multi-step processing. There is also ahigh expectation in this industry for safer and cost effective methodsfor manufacturing biocompatible implants avoiding the use of molds,which may lead to the need of further machining steps and/or to the useof substrate or binding agent. There is also a need for methods notinvolving the use of additives.

The present invention avoids the drawbacks of the prior art methods, asit is a one-step method for a direct manufacturing of a tridimensionalobject front a three-dimensional virtual object through lasertechnology, without using any mould.

The method of the invention is very advantageous in that it makes iteasy to shape an implant perfectly matching the shape of the defect siteand it does not involve the manufacturing of a specific mold for eachdefect. A close fit between the implant and defect site is desirablebecause (1) it can improve the healing of the defect after implantation,by for example facilitating the influx of cells, and (2) it ensure thatthe implant remains in the desired position within the defect. Thisinvention is not limited in any way regarding the shape of the workpiece, and makes it easy to manufacture complex, unique, customized workpieces, with an industrial scale. The method of the invention is alsoadvantageous as it may utilize any kind of material suitable with lasertechnology, for the manufacture of the implant.

Another advantage of the method of the invention is to result, ifdesired, in a biocompatible material having a controlled porosity.

Definitions

The term “biomaterial” as used herein means a material that isbiocompatible with a human or animal body. The biomaterial may becomprised within, or may be, an implant or tissue scaffold.

The term “porous” as used herein refers to a substrate that comprisespores holes or voids, rendering the biomaterial osteoconductive.Osteoconductivity typically refers to features associated with poreshaving a diameter equal or greater than approximately 10 micrometers,preferably from 10 to 1000 micrometers, more preferably from 100 to 800micrometers, still more preferably from 200 to 600 micrometers, evenmore preferably 300 to 500 micrometers.

The term “porosity” refers to a measure of the void spaces in thebiomaterial of the invention, and is measured as a fraction, between0-1, or as a percentage between 0-100%. According to the presentinvention, porosity is measured with SEM, i.e. Scanning ElectroMicroscopy (microscope JSM 6300 of the JEOL company, tension 15 KV):samples of “first area” are invested in a polymethylmethacrylate resin,and then polished and made conductor by the depot a thin layer ofGold-Palladium; 8 images (×20 scale) are acquired for each sample.Porosity is then assessed by a image analysis software using a techniqueof grey thresholding. The same method is applied to assess the porosityof the <<second area >=.

The term “powder” refers to a material composed of very fine particlesthat are not cemented together.

The term “particle” as used herein means a fragment or small piece ofmaterial.

The term “non-resorbable” as used herein means substantially notsusceptible to be absorbed or eliminated by an animal body, includinghuman body, through a physiological process.

The term “implantable” as used herein means capable to be surgicallygrafted, inserted or embedded in an animal, including human, body.

The term “first area” as used herein means an area of the implant thatis proximal and/or in contact with the borders or limits of the defect,and susceptible to be colonized in situ by the patient cells, such asfor example the patient osteoblasts. According to an embodiment, all orpart of the first area is colonizable by osteoblasts, and whencolonized, has mechanical properties very close to the mechanicalproperties of the adjacent bone. Advantageously, the first area iscolonized at its edge, which is very close or in contact with thenatural tissue when implanted. According to the invention, theosteoconductive porous first area is colonizable in situ withosteoblasts and behaves as a support for growth of osteoblasts.

The term “second area” as used herein means an area which may not becolonized in situ by the patient cells, because it is too distant fromthe borders or limits of the defect or because it is made ofnon-colonizable material, or because its low porosity does not make itpossible for the cells to colonize. In an embodiment, the second area istight.

The term “synthetic” as used herein means artificially produced

The term “substantially not degradable” means less than 10% ofresorbability by year.

DETAILED DESCRIPTION

This invention thus relates to a three-dimensional biomedical device,having an osteoconductive first area with a controlled porosity and asecond area, the device being produced by a laser technology from apowder comprising ceramics; and/or metals; and/or metal alloys; and/orbioactive glasses; and/or lead zirconate titanate; and/or biocompatiblepolymers and/or mixtures thereof.

Ceramics may be preferably selected from alumina or alumina derivativesuch as for example aluminosilicate; ceramic phosphates preferablytricalcium phosphate; apatite derivatives, preferably hydroxyapatite(including synthetic hydroxyapatite, more preferably substantially notdegradable synthetic hydroxyapatite, carbonate-substitutedhydroxyapatite, silicate-substituted hydroxyapatite); fluoroapatite orfluorohydroxyapatite or silicated apatite; zirconia, zirconiaderivatives, zirconia-toughened alumina (ZTA),alumina-toughened-zirconia (ATZ), alumina-zirconia, ytria-zirconia(TZP), wallostonite.

Metal and/or metal alloy are preferably selected from titanium; titaniumalloys such as for example titanium-aluminum-vanadium; chrome-cobalt andalloys thereof, titane-nickel alloys such as for example nitinol,stainless steel

Bioactive glasses are recognized as materials suitable for bone repairor replacement. Bioglasses preferred in the present invention aresilicate type materials composed of SiO₂, CaO and optionally Na₂O,and/or P₂O₅. Preferred bioglasses are those as commercialized under thename “Bioglass45S5”, or those having a composition as follows : 45-55%SiO₂, 10-25% (K₂O+Na₂O), 0-5% MgO; 10-25% CaO; 0-2% P₂O₅ and 0-1% B₂O₃in weight, to the total weight of the bioglass. A preferred bioglass hasthe following composition: 45% SiO₂, 24.5% CaO and 24.5% Na₂O and 6%P₂O₅ in weight to the total weight of the bioglass. Another preferredbioglass has the following composition: 53% SiO₂, 11% K₂O and 6% Na₂O 5%MgO 22% CaO and 2% P₂O₅ and 1% B₂O₃ in weight, to the total weight ofthe bioglass.

Lead zirconate titanate (Pb[ZrxTi1−x]O3 0<x<1), also called PZT, is aceramic perovskite material that shows a marked piezoelectric effect.

Biocompatible polymers suitable in this invention may be methylpolymethacrylate (PMMA), polyethylene (PE), PolyEtherEtherKetone (PEEK),polyglycolic acid (PGA), polybutylic acid (PBA), polylactic acid (PLLA),polycaprolactone (PCL)

According to a first embodiment, the biomaterial of the invention isnon-resorbable and uses non-resorbable materials only. According to asecond embodiment, the biomaterial is fully or partly resorbable.

According to a preferred embodiment, the three-dimensional biomedicaldevice of the invention, having an osteoconductive first area with acontrolled porosity and a second area, is such that the ratio of theporosity of the second area to the porosity of the first area beingequal or less than one, preferably ranging from 0.001 to 0.9, preferablyfrom 0.1 to 0.85, more preferably from 0.0111 to 0.83, more preferablyranging from 0.03 to 0.2, even more preferably from 0.033 and 0.166.

According to a particular embodiment the three-dimensional biomedicaldevice of the invention has an osteoconductive first area with acontrolled porosity and a second area, is produced by a laser technologyfrom a powder comprising a substantially not degradable hydroxyapatite,said powder being free of any metal or bone component, the ratio of theporosity of the second area to the porosity of the first area beingequal or less than one, preferably ranging from 0.001 to 0.9 preferablyfrom 0.1 to 0.85, more preferably from 0.0111 to 0.83, more preferablyranging from 0.03 to 0.2, even more preferably from 0.033 and 0.166.

Advantageously, the first area which is an osteoconductive porous matrixhaving a controlled porosity. The porosity (macroporosity) of the firstarea is preferably controlled by the 3D image laser. According to anembodiment, when the implant is placed in the defect, the first area,which is more porous than the second area, is contacting or close to thenatural tissue bordering the defect. Advantageously, the first area isat the periphery of the implant. Even more advantageously, the firstarea borders and surrounds the second area.

According to an embodiment, the pores of the first area have a diameter10 to 1000 micrometers, preferably from 100 to 800 micrometers, morepreferably from 200 to 600 micrometers, even more preferably 300 to 500micrometers.

Advantageously the porosity of the matrix is controlled in such a waythat the first 2.5 area behave as an osteoconductive support.Advantageously, the porosity in the first area may range from 20 to 90vol %, and preferably from 30 to 80 vol %. The term “vol %” means volumepercentage, corresponding to the ratio of the volume of vacuity to thefull volume.

According to another embodiment, the second area is such that itsporosity is comprised between 0 and 25 vol %, preferably 0 and 10% vol %more preferably of about 0 and 5 vol %. Consequently, the properties ofthe implant in the second area are different from the properties of theimplant in the first area. According to an embodiment, the second areaoccupies a larger surface in the implant that the first area.

According to an embodiment of the invention, the first area has acompression resistance ranging from 20 to 60 MPa, preferably rangingfrom 30 to 50 MPa, more preferably of about 40 MPa, the second area hasa compression resistance of 80 to 150 MPa, preferably 90 to 120 MPa,more preferably of about 100 MPa.

According to an embodiment, the biomaterial of the invention is suchthat the first area and the second area are made from the same initialpowder material, which preferably consists of synthetic hydroxyapatiteonly.

In this embodiment, the biomaterial of the invention is athree-dimensional multilayered biomedical device, having at least 2-1000layers, preferably 5-500 layers, more preferably 10-400 layers, eachlayer being made from one powder material.

According to an embodiment, the biomaterial may be a compositebiomaterial: in an embodiment, the biomedical has 2-1000 layers, least2-1000 layers, preferably 5-500 layers, more preferably 10-400 layers,and at least two layers being made from non-identical powder materials.

Advantageously, the first and last layers are of one material, such asfor example hydroxyapatite, and the inside layers are of a secondmaterial, such as for example a metal or metal alloy, advantageouslytitane or nitinol. In this embodiment, the finished implant may be suchthat its periphery is made of the one material, in our examplehydroxyapatite, whereas its core is made of the second material, in ourexample metal or metal alloy.

In another embodiment, the material is made of a porous colonizablefirst area, which may be hydroxyapatite or tricalcium phosphate and atight second area which may have a further function of reservoir fordrug release.

In a further embodiment, the biomaterial of the invention includes afirst peripheric area which may be hydroapatite, and a second core area,which may be TZP.

In a still further embodiment, the biomaterial of the invention includesa first area of hydroxyapatite, and a second area of ceramics such asfor example zirconia, or metal or metal alloy.

In a still further embodiment, the biomaterial of the invention includesa first area of tricalcium phosphate, and a second area of ceramics suchas for example zirconia, or metal or metal alloy.

The biomaterial of the invention may thus be non-uniformly porous.Non-uniform porosity allows for permeability (i.e. osteoconductivity) atsome regions and not at others, within the biomaterial, or the extent ofpermeability may differ within the first area, if needed. According toan embodiment, the first area is gradated from a high porosity at itsedge, to a lower porosity at its core.

According to another embodiment, the first and/or the second areaincludes spacers to make a biomaterial close to the alveolar bone, wherethe spacers play the role of the voids of the bone. The spacers are madeof ceramics and are means for maintaining spaces, preferably a hollowspace, within the biomaterial.

According to an embodiment, the biomaterial of the invention maycomprise one or more pharmaceutical agents or biomolecules, orcombinations thereof. The pharmaceutical agent may be any agent,although it is envisaged that the most useful agents will be those thate.g. promote healing, prevent infection, reduce inflammation, minimizeor prevent pain, stimulate the influx of healing cells, or act as aimmunosuppressant. The term “biomolecules” in this context includescells, for example stem cells or progenitor cells, The biomolecules maybe selected from the group consisting of: cells, cytokines, growthfactors, hormones or combinations thereof.

In a particular embodiment of the invention, first area, prior toimplantation, is seeded or colonized by tissue forming cellsimmunologically compatible with the eventual implant recipient.

In a particular embodiment of the invention, the first area, prior toimplantation, is seeded or colonized by tissue forming cells, such asfor example stem cells or stem cells derived cells, which are preferablyimmunologically compatible with the eventual patient, more preferablyautologous cells.

In a further embodiment, the first area, prior to implantation, isimpregnated with a cell growth medium suitable for osteoblasts growthand/or is in contact or impregnated with growth factors. It may thenseeded or colonized by tissue forming cells.

In a still further embodiment, the biomedical device of the invention isimplantable.

In a preferred embodiment, the biomedical device of the invention is animplant, preferably a three-dimensional implant, more preferably acranial implant. Preferably, this implant has a size suitable for largedefects, preferably equal or larger than 25 cm², more preferably 28-100cm². This implant may further comprise a sensor, such as for example asensor of biological signals, preferably intracranial pressuredetectors, electric micropotentials, etc.

In another embodiment, the biomedical device of the invention fits in abone defect.

In another embodiment, the biomedical device of the invention is acoating, which is coated onto an implant.

This invention also relates to a method for manufacturing a biomedicaldevice of the invention, wherein:

-   -   an image of the defect is performed through usual medical        imagery means, such as for example MRI (magnetic resonance        imaging), CT-scan (computerize tomography) and the image data        are consolidated in a three-dimensional software such as for        example “Mimics” of the MATERIALISE company in order to give a        three-dimensional view;    -   from this image, a virtual object is designed with a        computer-aid designed software known by one skilled in the art        such as for example “3-Matic” of the Materialise company or        “Cathia” of the Dassault Systems company;    -   optionally, a scale model (by model is meant a material subject        matter), i.e. a larger or smaller object than the actual size of        the virtual object designed with computer-aid software, or at        the actual size of said virtual object, may performed;    -   the design of the virtual object may be reviewed and optionally        corrected by the surgeon or following the instructions of the        surgeon;    -   upon agreement of the surgeon, the biomedical device is        manufactured by a laser technology comprising layering a powder        of particles, such as for example Ceramic particles, more        preferably substantially not degradable synthetic        hydroxyapatite, onto a plate so that a layer of a predetermined        thickness is formed on the plate, and having the laser beam        selectively processed the powder to produce a processed layer,        and this, layer after layer, the layers being joined together        until the completed part is formed.

The method of the invention is advantageous, in that it makes itpossible to directly manufacture biomedical devices, especiallyceramic-based biomedical devices, without needing a molding step or amachining step.

The method of the invention is flexible, in that the design mayperfectly be adapted to the defect and/or to the wishes of the surgeon.

According to an embodiment, the laser technology used in the process ofthe invention is laser powder fusion. In this embodiment, the particlesof the powder are directly fused when contacted with the laser beam,thus the process of the invention avoids the use of any binding agent.

The process is performed from at least one powder of particlescomprising ceramics; and/or metals; and/or metal alloys; and/orbioactive glasses; and/or lead zirconate titanate; and/or biocompatiblepolymers and/or mixtures thereof.

According to an embodiment, the particles consist of synthetichydroxyapatite. Advantageously, for large defects this synthetichydroxyapatite is substantially non-degradable. Preferably thehydroxyapatite powder has a purity of at least 95%.

According to another embodiment, the particles consist of tricalciumphosphate, preferably β-tricalcium phosphate.

According to a further embodiment, biphasic powder the particlescomprise or consist of a mixture hydroxyapatite/tricalcium phosphate ina ratio ranging from 55/45 to 90/10.

In a specific embodiment, the powder may be a mixture of particles ofvarious natures selected in the group of alumina, hydroxyapatite, B-TCP,Zircone and titanium, titanium alloys such as for exampletitanium-aluminium-vanadium, chrome-cobalt and alloys thereof.

The particles may have a granulometry of 1 to 500 micrometers,preferably 5 to 100 micrometers, more preferably 10 à 25 micrometers.

The plate may be slightly rough. This embodiment makes it easier for thefirst layer of particles to hook up onto the plate.

According to an embodiment, the layering device ix a titanium plate,possibly coated with a film of hydroxyapatite prior to the beginning ofthe building of the piece; the coating may be carried out by a powderprojection process such as for example “D gun”. This kind of coating ofthe plate may help having a good hook of the powder on the plate, andmay help the layering of the first layer.

According to an embodiment of the process of the invention, the powderis layered with a layering device; the layering device may be a roll,such as for example a ceramic roll. According to another embodiment, thelayering device is a blade, such as for example a metallic blade.

The thickness of the layer of powder may be adjusted at a predeterminedvalue, which may for example be of 10 to 1000 micrometers, preferably of50 to 500 micrometers, more preferably 70 to 100 micrometers.

According to an embodiment, the powder may be heated prior to thelayering step, at a temperature of 200 to 1500° C., preferably of 500 to1200° C., more preferably of about 800° C. The prior heating of thepowder may facilitate the processing of the powder.

According to the invention, the laser locally impacts the powder. Thelaser may be a pulsed laser or a continuous laser, preferably of 100 to250 watts, preferably of 160 watts. In an embodiment, the laser may be alaser YAG. The laser power of the laser beam may be adjusted at 1 to 25%of the total power of the laser, preferably at 5%, 7% or 10% of thetotal power. The laser may be partially defocused (for example 10% ofdefocusing).

At the point of impact of the laser, the powder of particles fuses. Thetrajectory of the laser, which is defined by computer means toreproduced the computer-aid designed object, defines the shape of theobject made from the processed particles, in the thickness of the layer.

The progression speed of the laser beam may range from 0.01 and 50 mm/s,preferably from 0.1 and 10, more preferably from 1 and 4 mm/s.

When a layer is processed, a further layer is spread and laserprocessed. The trajectory of the laser may have a deviation between thelaser beams and the deviation may range from 50 to 150 micrometers,preferably from 70 and 110 micrometers.

According to an embodiment, the plate is supported by a tray and thetray is movable up and down. In this embodiment, when a layer isprocessed, the tray is moved down prior to the processing of the nextlayer.

According to another embodiment, the plate is located within acontainer, which is preferably tight. Preferably, the container is afurnace or an oven, so that the powder may be easily heated.

Layer after layer, with reference to the 3D designed object, the fullbiomedical device is made. The non-processed powder is blown out.

According to an embodiment, a further optional step of thermicpost-treatment may be performed, wherein the biomedical device isreheated at a temperature of 200 to 400° C., preferably 250 to 350° C.,more preferably around 300° C. The final biomedical device is thenrecovered.

Another object of the invention is the use of a biomedical deviceaccording to the invention for replacing or filling of tissue defects,e.g. bone defects or cavities in animals, including humans.

According to an embodiment, the biomedical device of the invention maybe used as an implant repairing defects in bone structures resultingfrom surgery or trauma. In this embodiment, the biomedical device of theinvention may be useful to close a defect, such an opening in a skull,to protect the tissue underneath, e.g. brain tissue.

Thus, the biomedical device Of the invention is an orthobiologicaldevice, resulting in a porous scaffold. It may be used in traumatology,in reconstruction surgery, in regenerative surgery, in dental surgery,in orthodontia, in orthopaedic, in cell culture or any field ofapplication which could benefit from permanent biocompatible butsubstantially not degradable implant for reconstructive purposes or forfunctional purposes like drug delivery or pick-up of inner signals(intracranial pressure or electric potentials for instance) ortransmission of signals and/or energy from outer side of the body toinner side and vice versa.

More specifically, the biomedical device of the invention may be used asan implant to compensate bone losses such as: cranial lesions, calverialesions, due to traumas, tumors or malformation; maxillofacial honelosses (orbital and maxillary); dental lesions with significant loss ofalveolar bone.

Also, the biomedical device of the invention may be used as an implantto compensate bones losses in orthopaedic indications such as forexample traumatic lesions hard to consolidate, typically significantsegmental bone losses such as tibial pseudarthroses or non-union;primary bone cancer, typically Ewing sarcoma at the proximal femur; hipreplacement.

According to another embodiment, the biomedical device of the inventionmay be a synthetic bone, preferably a hydroxyapatite synthetic bone, onand/or in which stem preferably autologous stem cells, may have beenseeded and/or cultured.

According to a particular embodiment, this invention is directed to anorthopedic implant for implantation into bone cavities to support bonetissue adjacent to the cavity The present invention will become morefully understood from the detailed description given herein below andthe accompanying drawings which are given by way of illustration only,and are not intended to limit the scope of the present patentapplication.

FIG. 1 is schema of a suitable device to implement the process of theinvention.

EXAMPLE

The machine used may be a Phenix® PM100 device commercialized by PhenixSystems®.

A ceramic powder of hydroxyapatite having a granulometry 10 to 25micrometers (commercial reference Medicoat®/Medipure®20-15, purity>95%)is placed in a container 1 so that it can be layered on a plate 2. Thetray 2 may be located in the furnace 3 of the machine 6. The powder maybe heated to 800° C. The plate 2 may be supported by a tray 10 movableup and down. The powder is layered with a ceramic roll 5 at a place 7,where it will be processed by a laser beam 8 release from agalvanometric head 9 (computer directed optical susceptible to direct alaser beam with high speed and high precision). The thickness of theresulting layer is of about 100 micrometers. A laser YAG 160 Watts ispreferably used to locally impact and process the powder. The power ofthe laser beam may preferably be adjusted to 10% of the total power ofthe laser in order to avoid vitrification of the ceramic powder thelaser beam may be 10% defocused; the laser deviation may be 80micrometers; the progression speed of the laser beam may be of 4 mm/s.The trajectory of the laser is defined by the 3D-image.

The data of the image (CT scan or IRM for example) are exported in asuitable format, for example DICOM. This file is imported in a softwarewhich carries out a partition of the various level of grey and, startingfrom various cut-offs, rebuilds the three-dimensional anatomy of thedefect. From this 3D file and a computer mediated design software, it ispossible to conceive the macrostructure of the implant that fits thedefect.

A first area, preferably located at the periphery of the structure, maybe a matrix-type microstructure colonizable by the patient'sosteoblasts.

The design of the implant is exported in a suitable format (for exampleformat STL, IGES, DXF, HPP, OBJ) to the rapid prototyping machine, andis cut-off in slices corresponding to the thickness of the layers (forexample, format SLC). The information for each layer defines thetrajectory of the laser.

The trajectory of the laser designs the shape of the 3D-image in thepowder, actually in the thickness of the powder. When a layer isprocessed, the tray supporting the plate is moved down at a distancecorresponding to the thickness of a layer and the next layer of powderis layered. The process is repeated until the full biomedical device isproduced. The laser beams processes, preferably fuses the ceramicparticles together in the whole thickness of the layer and it actionpropagates also on the preceding layer, so that the current layer andthe preceding layer actually are fused together.

At the end of the process, the not-fused residual powder is blown out byany suitable means, preferably mechanical means such as for examplemicro-aspiration or suction or brushing; then, the biomedical device isrecovered.

1. A three-dimensional biomedical device, having an osteoconductivefirst area with a controlled porosity and a second area, the devicebeing produced by a laser technology from a powder comprising a materialselected from the group consisting of ceramics, metals, metal alloys,bioactive glasses, lead zirconatetitanate, biocompatible polymers, andmixtures thereof, the ratio of the porosity of the second area to theporosity of the first area being equal or less than one.
 2. Thebiomedical device according to claim 1, wherein the powder comprises orconsists of ceramics selected from the group consisting of alumina oralumina derivative, ceramic phosphates, apatite derivatives, zirconia,zirconia derivatives, zirconia-toughened alumina (ZTA),alumina-toughened-zirconia (ATZ), alumina-zircona, ytria-zirconia (TZP),and wallostonite.
 3. The biomedical device according to claim 1, whereinthe powder comprises or consists of a mixture hydroxyapatite/tricalciumphosphate in a ratio ranging from 55/45 to 90/10.
 4. The biomedicaldevice according to claim 1, wherein said bioactive glasses are silicatetype materials comprising SiO₂, CaO and optionally Na₂O, and/or P₂O₅. 5.The biomedical device according to claim 1, wherein the pores of thefirst area have a diameter from 10 to 1000 micrometers.
 6. Thebiomedical device according to claim 1, wherein the porosity of thefirst area ranges from 20 to 90 vol %.
 7. The biomedical deviceaccording to claim 1, wherein the first area, prior to implantation, isseeded or colonized by tissue forming cells immunologically compatiblewith the eventual implant recipient.
 8. The biomedical device accordingto claim 1, wherein the first area, prior to implantation, isimpregnated with a cell growth medium and/or growth factors suitable forosteoblasts growth.
 9. The biomedical device according to claim 1, whichis implantable.
 10. The biomedical device according to claim 1, furthercomprising a sensor.